Process of routing articles through a furnace



Oct. 22, 1940. R. c. INGERSLL 2,218,935'i v PRocEss oF nou'rlue ARTICLES 'ranouou A runnen -Filed Dec. 30, 1956 {Sheets-Sheet 1 llll'IlL Il1ll nsoZZ pct. 22. 1940.

R. c. `lNGERsoLL vPROCESS QF ROUTING ARTICLES THROUGH A IURNACE Fixed xm. so. nassv 2 Shoots-Shoot 2 Patented Oct. 22. 1940 2.21am raocass or non'rmc ARTICLES THROUGH A nummer;A

Roy C. Ingersoll, Oak Park, Ill., assignor to Borg- Warner Corporation, a corporation of Illinois Application December 30, 1936, Serial No. 118,312

4 claims. (o1. zs-'ls'n luNrrlszDl STATES PATENT OFFICE 'I'his invention has to do with the processing of material by subjection to heat, and relates particularly to improvements in the mode of moving the material thereby effecting a diminution in heat loss. For example, the present invention may be applied inthe art of preparing enamelled surfaces upon articles of manufacture or the like. Almost universally enamelware is baked in a box furnace into which the articles to be treated are introduced through an opening and later removed through the same opening. 'Ihis methd'in addition to being slow and making but an ineiiicient use of the furnace has the further undesirable feature of causing sudden temperature changes in the enamelware. Articles which have been coated with green enamel are preferably'gradually brought up to a temperature at which such enamel will become hardened by baking and then gradually cooled to room temperature. This process in a few instances has been successfully performed in large continuous type of ovens or furnaces through which a line of freshly coated articles are successively transported within a space having a temperature gradient which iirst increases in the direction of the line movement and then de-v creases'in the direction of line movement toward an oven exit. Usually in such ovens portions of the lines of ingress and egress are in close proximity so that incoming articleswill absorb heat from and gradually cool those being carried toward the oven exit. Obviously the large amount of space required for anoven. of this type and i the original cost of such an installation are objectionable factors.

Another object of the present invention is the provision of an expedient method ofrecouping heat from furnace treated articles for energizing a pre-heater chamber wherein succeeding articles are heated prior to disposal insuch furnace.

Still another object of the present invention is the provision of a novel method of heat treating articles by introducing successive groups thereof into an oven and withdrawing the same from the oven into a position below succeeding untreated articles for preheating them prior to their advancement into the oven. 1

Other objects of the invention will become apparent upon reading the following description Y with reference to the accompanying drawings,

wherein:

Fig. 1 is a fragmentary side elevation of a unitary structure of ring chamber and preheating chambers, a side wall of the furnace and preheating chambers being removed to expose the interior of the unit;l

Fig. 2 is a transverse sectional view taken on the line 2-2 oflFig. 1; and

Fig. 3 consists of a series of diagrammatic repdling washing machine tubs which are coated with a suitable substance adapted to be baked for forming a hard enamel surface when subjected to adequate heat. vIt is to vbe understood, however, that theapparatus and process may be modified to extend to heat treatment of other articles or materials without departing from the spirit of the invention.

Referring now to Fig. l, there will be seen a furnace I0 resting upon a foundation II. End. walls I2 and I3 of the furnace have therein openings I 4 and I5 which may be closed by vertically movable doorsA I6 and I1. A conventional style offurnace burner is indicated at I8.

Identical heat recuperator or preheating chambers I9 and 20 are arranged oppositely with respect to the firing chamber I0. The openings I4 and I5 in firing chamber I0 communicate respectively with the chambers I9 and 28 when the firing chamber doors I6 and I1 are raised by means of cables 2| and 22 which'are adapted to be Wound upon drums 23 and 24. Openings 25 and 26, closable by doors 21 and 28, are provided in the preheating chambers I9 and 20. Said doors 21 and 28 are adapted to be elevated-by means Aof cables 29 and 30 which are adapted to be wrapped about drums 3I and 32.

A conveyor comprised of endless chains 33 is engaged by driving sprockets 34 and 35. The upper spans 36 of the chains 33 are maintained in a common horizontal plane by means of channels 31, which longitudinally traverse the entire unit. Channels 31 are in alignment with and extend designated respectively A, B, C and D. Each burning bar 4I has upright pointed pins 4I* for .supporting an article 42 in a manner making contact with a minimum of the area thereof. The size of the present unit of firing chamber and preheater chambers is such as to accommodate sets A, B, C and D each of which consists of five burning bars. Obviously the size and number of burning bars in a set may be changed and still remain within the scope oi the invention.

Upon referring to Fig. 2, it will be seen that each burning bar 4I is adapted to support two articles to be treated by the furnace, and that such burning bars extend transversely of the chains 33. Also in Fig. 2, it will be noticed that the ends of the burning bars 4I project beyond the chains 33 so that such ends may be engaged on their underside by the horizontal wings oi' angle pieces 43 carried by a cradle 44. Cradle 44 is supported upon cables 45, which are adapted to be wound upon drumsv46 carried by a shaft 41. Power driving means including gearing 48 is adapted to rotate the shaft 41 and the drums 46 for raising and lowering the cradle 44 by means of the cables 45. The cradle 44 is illustrated in Fig. 2 as supporting group B of the burning bars in the upper part of the preheating chamber I9. Group D of burning bars 4I is shown in Fig. l as supported in the upper part of preheating chamber 20 by a similar cradle device of which only the angle member 431s shown.

Prior to Itheir introduction into the preheating chambers of the device, the tubs 42 are loaded onto a set oi burning bars 4| w-hich are resting upon a charging fork 43 or 50, Fig. 1. Subsequent lto loading a group of burning bars carrying tubs 42 upon a fork 49 or 50, the chamber door 21 or 23 is opened and the 'fork projected into its chambei I9 or 20. The fork is then lowered whereby to deposit the -group of burning lbars upon the conveyor chains 33. The forkis then withdrawn andthe chamber door closed. While the load'is being depoated Within a chamber the cradle 44 therein is in its lowermost position so :that the load is actually deposited within the confines oi a cradle. As soon as the loading fork has been withdrawn from the chamber the cradle 44 is elevated to :lift the group of burning bars and articles 42 Ithereon atter the fashion illustrated in-Flg. 2. Thereafter, a load o f treated articles is withdrawn from 'the rlng chamber I0 and deposited within the preheating f chamber beneath :the articles which have Just been elevated. The door I3 or I1 of the tiring chamber Il is closed behind rthe articles moved therefrom into the chamber I9 or `20, said ar- -ticles being permitted :to remain in 'the chamber to give up part of their heat for preheating the elevated articles. Eventually, the ilred articles are removed from the preheating chamber by means of a fork 49 or 50. The removed articles are then taken from the burning bars and replaced by fresh articles which are later inserted into the preheating chamber and elevated.

A coordinated order of manipulating the vanious groups of burning bars as an incident .to carrying out Ithe improved process will best be understood by reference to Fig. 3 where the sixteen successive stages of a preferred cycle are shown. The groups of burning bars are lthere designatedA,B,CandDasinFigs.1 and2. In

the inception it should be conceived that groups A and B are rotatively shifted between positions at Ithe left-hand -load and unload end of the unit, in the preheating chamber I9 Iand in the firing chamber III; whereas groups C and D are similarly rotated between positions at the right load and unload end of the unit in -t-he preheating chamber 20 and in the iiring chamber III.

Burning bar groups A and C are shifted into returned to the preheating chamber lfrom which it had been taken, at which time fthe conveyor will :be given |a reverse movement.

While the conveyor is moving for shifting groups of burning bars, both iring chamber doors I6 and I1 are open, so 'that incident to carrying one group of vburning bars into the rlring chamber from one of the preheating chambers, a group of burning bars carrying a load of treated .articles will be removed from the ring chamber into the opposite preheating chamber. Upon the completion of the movement of the conveyor .the tiring chamber doors I6 and I1 will be closed. At no :time is a preheater door 21 or 28 open while :the opposite firing chamber door I6 or I1 is open, this precaution being taken so as to conserve heat which may otherwise be lost through radiation. Inasmuch as any conventionally controlled driving means may be employed for reversibly driving rthe chains 33 of the conveyor, no means is illustrated in 'this application.

Referring now to the rst stage shown in Fig. 3, the arrow indicates that group A of burning bars has just been removed from preheating chamber I9 and disposed at the lett end of the unit for having unloaded therefrom articles which have been treatedin the lining chamber I0, and for reloading with I-resh articles. Group B of vburning bars has remained in the elevated position in preheating chamber I3 while the load A was removed through chamber opening 25 by means of the loading fork 49. Group C o! loaded burning bars is in the iiring chamber, and Group D of such bars is in the elevated position in preheating chamber 20.

In the nex-t or second stage of Ithe cycle, group A remains in position for unloading and reloading. Group B has been lowered, as indicated by the arrow, -from lthe position shown in stage I to the lower position in preheating chamber I9. Groups C and D remain as in the rst stage.

In the .third stage, groups B and C which have been resting upon the conveyor chains 33 are moved through firing chamber door openings I4 and I5 by a movement of the conveyor and placed in the .positions indicated by the arrows. As

soon aas groups B and C are'thus placed, the

` by the arrow in. stage 4. Meanwhilathe heat from group C has been -heating the chamber 2l.

. asians As the cycle proceeds, however, group C is rea moved from the chamber Il as shown by the arrow oistage 5.

In the next stage, stage ll. group D is lowered as indicated by fthe arrow, Ithis group having been preheated during the' tive preceding stages. lowered group D is placed upon the conveyor chains 33- for movement thereby into the firing chamber III as shown in ustage 1. It will be noted that when the conveyor reversed its movement for moving group D into .the tiring chamber, bolt/h ringchamber doors I6 and I1 were raised so that group B was concurrently carried out of the firing chamber. The heated load ofarticles in group B then serve to give out heat in .the preheating chamber II -to runt-her prehea-t the articles in 'group A.

During stages 8 and l1 group C is unloaded and loaded with fresh articles, and during stage 8, group C is'issued into Ithe preheating chamber 20 and elevated. Next stage 8, group B is taken from 4prehealting chamber I9` and group A is lowered upon the conveyor as shown in stage I0.

Groups A and D are then resting upon the conveyor in readiness to be shifted tothe rightas shown in stage I I, whereby group A is moved into the firing chamber, and group D is moved into the preheating chamber 20 for imparting heat thereto. During stages I and ll, `group B was unloaded and loaded with fresh articles, and during stage I2 said group is issued into the preheating chamber IS and elevated. By the time of arrival for stage Il, group D has heated Ithe preheating chamber 2l and is removed therefrom as shown by the arrow. In stage I4 group C is shown to |have been lowered upon #the conveyor, whereby such group C which Ihas been preheated may be moved into the ilring chamber concurrently with the removal of group A from the firing chamber incident to rthe'movement of the conveyor as indicated by the arrows in stage I5. Group D, which has then been unloaded and loaded with fresh articles for heat treatment, is then issued into preheating chamber 20 as shown in stage I6. Stage I6 completes the cycle. 'Repetition of the cycle 'is commenced by removing group A from the preheating chamber I9 to the position shown in stage I. The process may then proceed through the various stages dn the manner above described.

Although this specification shows and describes a cham-conveyor for moving the material into and out of the furnace I0, it is to be understood that any other suitable means such as hearth furnace rollers, carrying cradles, a unit comprised of burning bar and cradle may be used.

When, for example, hearth furnace rollers (or any kind of support means having slight resistance to movement of objects thereover) are used instead of a. chain conveyor for supporting the groups of burning bars within the preheaters and ring chamber, the loading forks I9 and 50 may be employed for inserting and withdrawing the groups into and out of the firing chamber. It

will be understood that the hearth rollers will be rotatable about axes' disposed transversely of the path traversed by the articles so that the advanced end of afork 49 or 50 may simply be pressed against an end of a group of burning bars for pushing them from a chamber I9 or 20 into the firing chamber. Both ilring chamberv doors I6 and I1 will be raised at such time so that the treated in the firing chamber whereby the latter from each other.

group is ejected into the opposite preheater chamber. Thereafter, the fork is withdrawn and the firing chamber doors I8 and I1 closed as well as the door 21 or 2B through which the chargingfork had been projected. 'I'he manner in which the hearth rollers and charging fork may be `used yin the process in place of the chain conveyor is further exempliiled by reference lto positions 2, 3 and 4 vof Fig. 3. In position 2 the fork 4l is loaded with untreated articles; group B has been lowered in readinessfor movement into the firing chamber I0; and group C is in conditionV for movement from the nring* chamber. Preheater door 21 and ilring chamber doors I6 and I1 are nowvopened while the fork 49 is advanced to the right for depositing group A in preheater I8 and for moving groups B and C respectively into the ilring chamber and into the preheater 20 as illustrated 'in position 3. The charging fork is then withdrawn, doors I6, I1 and 21 closed, and group A elevated as shown in position 4. A previous explanation has been given with respect to the manner in which the charging fork 50 removes group C'from preheater chamber 20 as shown in position 5. After group C has been reloaded the charging fork lSli is used for introducingv such group into preheater 20 While latvthe same time shifting groups B and D in the manner indicated gather heat from articles thereunder which have just been removed from th firing chamber and also absorb such heat as is released into the preheater through the opening I4 or I 5 during the periods the door for such opening is raised. The articles supported in the upper part of a preheater chamber benefit from articles removed from the ring chamber and placed thereunder, the benefit being derived from the heat absorbed from the lower articles. Meanwhile the temperature of the lower articles is reduced because of the heat given up to the elevated articles, so that it will be seen that the preheater enables the ingoing and out-coming articles to mutually benefit The partially cooled articles emerging from the preheaters do not encounter a too pronounced change in temperature upon being subjected to the? atmosphere as may be the the heated air limmediately'rises from the hot7 lower articles to the cooler upper ones, thus greatly increasing the amount of heat exchange between the articles within a given period.

When consideration is taken of the small size together with the heat conservation faculties of my improved apparatus for carrying out the novel process hereinabove described, special note will be taken of the rapidity with which articles may betreated therein'. Although `the specic apparatus and process which have been described are extremely useful it will be understood that the invention is not limited with respect thereto excepting as regards the novel principles underlying the same asset out in the appended claims.y

1'. The process of routing articles through a. furnace'comprising a firing chamber and preheating chambers positioned on opposite sides of the firing chamber, said process comprising the steps of charging said firing and preheating chambers with loads of such articles, discharging a heated load of articles from the firing chamber into a preheating chamber on one side of the firing chamber while simultaneously charging the firing chamber with the load from a. preheating chamber on the oppositeside of said firing cham,

furnace comprising a firing chamber and preheating chambers positioned on opposite sides of the ring chamber, said process comprising the steps of charging said firing and preheating chambers with loads of such articles, and alternately charging the tiring chamber with loads from said preheating chambers, the loads being returned from the ring chamber to the preheating chambers from which they were taken while simultaneously charging the nring chamber with loads from the opposite preheating chamber.

3. The process of routing articles through a furnace comprising a ring chamber and preheating chambers positioned on opposite sides of the firing chamber, said process comprising the steps of charging said ring and preheating chambers with loads of such articles, alternately charging the firing chamber with loads from said preheating chambers, the loads being returned from the firing chamber to the preheating chambers from which they were taken while simultaneously charging the nring chamber with loads from the opposite preheating chamber, and discharging a fired load from a. preheating chamber while a load from the opposite preheating chamber is being nred.

4.' The process of routing articles through a furnace as described in claim 3, and charging the preheating chamber from which a red load has been discharged with a fresh load to be preheated, said charging being done while a load from the opposite preheating chamber is being red in the ring chamber. y

ROY C. INGERSOLL. 

